It is a persistent problem in building construction that materials and construction elements of a variety of constituent materials must be joined together to form the building. Windows of glass must be fitted into frames of metal, wood or plastics, window frames must be fitted into the sustaining walls, which are typically made from concrete or bricks; and the walls must be secured to the buildings foundation in order for the building to remain standing. In particular in modern buildings, construction elements very often arrive prefabricated at the building site and are inserted into the building's frame work with minimal or no adaptation of the prefabricated construction element.
In many cases, such as a window frame being fitted into a brick or a concrete construction, the construction element arrives prefabricated with a dimension which is smaller by a significant margin (often dictated by governmental standards), leaving a gap between the prefabricated construction element and the building proper. While this is advantageous as it eases the insertion of the prefabricated construction element into the building and minimizes any subsequent adaptation, the joints between the element and the building proper must necessarily be closed prior to human use of the finished building.
The process of closing such joints between building elements is known as caulking and the materials used are considered caulks. The function of caulking is to provide thermal insulation, and control of water penetration and of noise mitigation.
Historically, caulks were either mortar or plasto-elastic materials such as e.g. pitch. Today a variety of caulks are known. In particular plasto-elastic materials, known as sealants, are ubiquitously used in the building industry. In this respect, plasto-elastic materials have the advantage over mortar that they are easy to apply, normally using a handheld caulking gun, and will retain a fluid-tight joint seal over many years all the while permitting the different construction materials the freedom to become displaced relative to each other with the varying weather conditions experienced by the building during the lifetime of the sealant.
Numerous construction chemicals are sold as caulk such as e.g. silicone, and acrylic sealants. Unlike construction caulk, which is applied where no building movement is expected, a sealant is made of elastomeric materials that typically allow movement of 25% to 50% of the width of the joint. Silicone sealants form a durable, water-tight seal, but are not typically paintable. Some silicone sealants are made to be paintable with certain types of paint such as water or oil-based paints. Other sealants are paintable.
Sealants are commonly sold in cartridges which are loaded into a pistol-like caulking gun (opening at the side) or barrel gun (opening at the end) for application. During the tool-working time, which varies by chemistry, the caulk can be pressed into the joint so that it can bond with the materials on both sides, and also be smoothed. The time it takes for a chemical sealant to become a sealing rubber is known as the curing time and varies by temperature and humidity. It is an advantage of modern sealants that they bond well to the various surfaces encountered in modern building construction materials.
A problem of modern plasto-elastic sealant materials when used as caulks compared to mortar is leakage of plasticizers over time. This reduces the strength of the seal and can lead to costly and time consuming re-caulking of the joint. Another problem compared to mortar of modern plasto-elastic sealant materials when used as caulks is the low diffusivity of the sealant material for water.
In a building, water is ubiquitously present both indoors as well as outdoors. Trapping water inside a building will lead to significant problems with mold growth and an associated and very significant health risk to the individuals living inside the building. Permitting the water to leave the building by venting the building or by actively removing moisture using air condition systems is therefore necessary. However, at cold spots or next to water impermeable surfaces, water will accumulate and molding may occur.
This problem is particularly persistent where modern sealants are applied as caulks as these are not diffusion open to water. Such sealants are therefore often attacked by molds leading to unaesthetically looking joints and potentially posing health risks. Further, the vapor barrier created by the water tight seal will be at the wrong (indoor) side of the building. This may cause wooden window frames or wallpaper next to the joint to mold, which can be costly in repairs and poses a potential health risk. Hence it is an object of the present invention to suggest improved caulks which at least partially will overcome the problem of molding of the joint during the joint's life time.
Another aesthetic problem of modern sealants compared to mortar is related to the color of the seal. Modern sealants generally do not have an aesthetically pleasing color compared to a building's surface, often differing significantly from the colors of the other building materials. It is therefore another aspect of the present invention to suggest improved caulks which at least partially will overcome this problem and wherein the improved caulks of the invention have a color and an appearance traditionally associated with mortar, yet retaining the ease of applicability and good adhesive properties associated with modern sealants.
A further problem of modern sealants is their relative high cost per volume. This repeatedly creates the need for filling the intermediate volume between the building objects with cheaper filling material, typically an insulating material, prior to application of the sealant. This adds an additional handling step in the construction process, requiring additional man power and man time, which is an unnecessary added cost. Accordingly, there is further the need for a caulk which is insulating yet less expensive compared to modern sealants.
To these purposes the present inventors suggest the use of a composite caulk comprising paper wool, perlite, a particulated wood material having a particle size below 2 mm, a particulated fire retardant bark material having at least one axis of length with a dimension below 2 mm and a polyvinyl-acetate based aqueous dispersion adhesive; and wherein the composite caulk forms a heterogeneous caulk which can be dispensed using a handheld caulking gun.
In the art, U.S. Pat. No. 3,468,414, it is known to make instant paper mache which comprises perlite as a mechanical binder or filler for enhancing the porosity of the paper mache following its ultimate usage and drying. The compositions of U.S. Pat. No. 3,468,414 contains in percentage by weight: Paper (80% newspaper, 20% magazine) 45.7-47.2%, art or molding plaster 16.6-17.2%, perlite 9.7-17.1%, borated dextrin 5.6-7.9%, salt 4.3-6.6%, starch 4.3-11.1%, and carboxy methyl cellulose 4.2-5.7%; and were found suitable for making simple preformed building elements, such as e.g. bricks. However, the prior art is silent on the composite caulks of the present art as well as their intended use.